Minimally invasive pedicle screw extension sleeve system

ABSTRACT

An embodiment includes a system comprising: a tulip including a slot to receive a linkage, first and second side walls that define a portion of the slot, and a ring that couples the first side wall to the second side wall; wherein the ring couples to the first side wall at a thinned first proximal fulcrum and to the second side wall at a thinned second proximal fulcrum and the ring pivots about the first and second proximal fulcrums when the ring is forced proximally; wherein the first side wall includes a first sidewall projection that projects past the first proximal fulcrum and the second side wall includes a second sidewall projection that projects past the second proximal fulcrum. Other embodiments are described herein.

CLAIM OF PRIORITY

This application is a continuation of U.S. patent application Ser. No.15/981,445, filed May 16, 2018, which is a continuation of U.S. patentapplication Ser. No. 14/765,402, filed on Aug. 3, 2015, now U.S. Pat.No. 10,004,543, issued Jun. 26, 2018, which is a 371 National StageEntry of International Application No. PCT/US2014/014661, filed on Feb.4, 2014, and titled “Minimally Invasive Pedicle Screw Extension SleeveSystem”, which claims priority to U.S. Provisional Patent ApplicationNo. 61/760,385, filed on Feb. 4, 2013, and titled “Minimally InvasivePedicle Screw”. The content of each of the above applications is herebyincorporated by reference.

BACKGROUND

Spinal fixation devices can be used to provide, for example,immobilization and stabilization of spinal segments in patients (e.g.,humans, dogs, cats, and other animals). Fixation devices may be used tohelp fuse bone segments (e.g., vertebrae) in the treatment ofinstabilities or deformities of, for example, the cervical, thoracic,lumbar, and/or sacral spine. Such instabilities or deformities mayinclude, for example, degenerative disc disease (DDD);spondylolisthesis; trauma (i.e., fracture or dislocation); spinalstenosis; curvatures (i.e., scoliosis, kyphosis, and/or lordosis);tumor; pseudoarthrosis; and failed previous fusions.

FIGS. 1A, 1B, 1C, 1D, 1E depict a conventional spinal fixation system.FIG. 1A includes a fixation screw 101 located at the distal end ofextension sleeve system, sometimes referred to as a “tulip”. Morespecifically, screw 101 is included in the “saddle” 107, which couplesto sleeves 102, 103. The sleeves are separated from each other bywindows 105, 106. There is a circular recess 108 near the distal end ofthe system. FIG. 1B shows the same system as FIG. 1A but without screw101 deployed in the saddle 107. FIG. 1C shows a side view of the samesystem. FIG. 1D shows a 90 degree rotation from the perspective of FIG.1C. FIG. 1E shoes a close up of the proximal end of the system of FIG.1B. Screw 101 may be deployed through orifice 109, down between sleeves102, 103, and into saddle 107 and bone (e.g., pedicle, femur, humerus)that connects to saddle 107. Screw 101 may be inserted using an implantdevice, such as a screw driver, that is also inserted into orifice 109or windows 105, 106. The two arms 102, 103 collectively couple to oneanother via ring portions 110, 111 at the proximal end of the tulip.

In greater detail, a physician slides screw 101 through the orifice 109and into saddle 107. In some instances the screw may already be locatedin the saddle when the physician receives the system. After the screw isimplanted into bone the physician will remove and/or break the ringportions 110, 111. By breaking the ring portions the proximal arms orsleeves 102, 103 are no longer directly connected to one another at theproximal end of the system. Instead, sleeves 102, 103 only indirectlycouple to one another via saddle 107. So by breaking the ring portions110, 111 (e.g., at one location 115 above window 105 and at anotherlocation 116 above the other slot or window 106), the proximal portionsof arms 102, 103 may be moved independently of each other. Now thephysician may “work” or bend back and forth the two arms 102, 103. Doingso helps fatigue the system at the distal ring 108 so that the armsbreak off from the saddle 107 at distal ring 108, thereby leaving onlythe saddle and screw in the patient. The two arms 102, 103 from thetulip may be removed.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of embodiments of the present invention willbecome apparent from the appended claims, the following detaileddescription of one or more example embodiments, and the correspondingfigures, in which:

FIGS. 1A, 1B, 1C, 1D, 1E depict a conventional spinal fixation system.FIG. 1A includes a fixation screw located at the distal end of anextension sleeve system. FIG. 1B shows the same system as FIG. 1A butwithout the screw. FIG. 1C shows a side view of the same system as FIG.1A. FIG. 1D shows a 90 degree rotation from the perspective of FIG. 1C.FIG. 1E shoes a close up of the proximal end of the system of FIG. 1B.

FIGS. 2A, 2B, 2C, 2D, 2E, 2F, 2G, 2H, 2I, 2J depict an embodiment of theinvention. FIG. 2A includes a fixation screw located at the distal endof an extension sleeve system. FIG. 2B shows the same system as FIG. 2Abut without the screw. FIGS. 2C, 2D show different perspective views ofproximal portions of the extended sleeve embodiment. FIGS. 2E, 2F showside views of proximal portions of the extended sleeve embodiment. FIGS.2G, 2H show front and rear views of proximal portions of the extendedsleeve embodiment. FIGS. 2I, 2J show dimensions of proximal portions ofan embodiment of the extended sleeve system.

FIG. 3A shows a proximal end of a sleeve system before a linking ring isremoved and the proximal ends of sleeves are disconnected from oneanother. FIG. 3B shows a hook member seizing the proximal linking ring.FIG. 3C shows the hook member pulling on the linking ring therebycausing a fracture at thin portions of the sleeves. FIG. 3D shows thesystem after the linking ring has been removed thereby leaving a sharpedge protected by protrusions on either side of the sharp edge.

FIGS. 4A, 4B, 4C, 4D, 4E depict an embodiment of the invention. FIG. 4Aincludes a fixation screw located at the distal end of an extensionsleeve system. FIG. 4B shows the same system as FIG. 4A but without thescrew. FIG. 4C shows a different perspective of FIG. 4B. FIGS. 4D, 4Eshow different perspective views of proximal portions of the extendedsleeve embodiment.

FIGS. 5A, 5B, 5C depict a method of implanting an embodiment of theinvention. FIG. 5A depicts three tulip structures with protectiveproximal rings already removed. FIG. 5B shows the physician accessingthe channels between sleeves for all three of the tulip structures. FIG.5C shows the physician implanting a linkage rod that will link threedifferent pedicle screws.

FIG. 6 depicts a method of implanting an embodiment of the invention.

FIGS. 7A, 7B, 7C depict a method of implanting an embodiment of theinvention. FIG. 7A depicts two tulip structures with protective proximalrings still present. FIG. 7B shows the physician accessing the channelsbetween sleeves for both of the tulip structures. FIG. 7C shows thephysician implanting a linkage rod that will link two different pediclescrews.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forthbut embodiments of the invention may be practiced without these specificdetails. Well-known structures and techniques have not been shown indetail to avoid obscuring an understanding of this description. “Anembodiment”, “various embodiments” and the like indicate embodiment(s)so described may include particular features, structures, orcharacteristics, but not every embodiment necessarily includes theparticular features, structures, or characteristics. Some embodimentsmay have some, all, or none of the features described for otherembodiments. “First”, “second”, “third” and the like describe a commonobject and indicate different instances of like objects are beingreferred to. Such adjectives do not imply objects so described must bein a given sequence, either temporally, spatially, in ranking, or in anyother manner “Connected” may indicate elements are in direct physical orelectrical contact with each other and “coupled” may indicate elementsco-operate or interact with each other, but they may or may not be indirect physical contact. Also, while similar or same numbers may be usedto designate same or similar parts in different figures, doing so doesnot mean all figures including similar or same numbers constitute asingle or same embodiment.

As described above with regard to FIGS. 1A, 1B, 1C, 1D, 1E, modularextended tulips are used for minimally invasive spine surgery. Thevarious types of tulips range from flexible snap on tulips to fixedone-piece tulips. A problem with the modular based tulip extensions isthat they have a tendency to release from the tulip or saddleunexpectedly. A problem with existing fixed one-piece tulips is thatthey are either too flexible and/or they are difficult to separate attheir tops prior to breaking the tulips off from pedicle screws at theend of the surgery. The existing fixed one-piece tulips requireadditional steps to separate. Generally, they require the surgeon to cutthe joining piece on the tulips, such as portions 110, 111 of FIG. 1E.This necessitates an additional surgical step and also opens thepotential for leaving a remnant of the tulip in the patient or leaving asharp remnant that can cut the surgeon or patient. For example, aphysician that cuts each of 110 and 111 in half (for example, at areas115, 116) will then have sharp edges at these cut points. Specifically,there will be two sharp points at the cut line 116 in member 111 andthere will be two sharp points at the cut line 115 in member 110.Furthermore, the sharp points will be exposed and unprotected as thearms 102, 103 are moved away from each other. The sharp points pose ahazard to the physician, the operating personnel (e.g., scrub nurses),and the patient.

In contrast to conventional systems, an embodiment of the inventionincludes a minimally invasive pedicle screw system consisting of anextended 5.75″ fixed one-piece titanium tulip (e.g., FIG. 2A) with aspecial milling pattern (e.g., portions 220, 221, 222 addressed below)combined with a cannulated screw. Other embodiments are not limited to5.75″ dimensions and may be shorter, longer, wider, and/or skinnier.This allows a screw to be inserted into the surgical site over a k-wirethrough a very small surgical incision. The extended tulip arms aid inboth the retraction of soft tissue as well as helping the surgeon tovisualize the orientation of the screws in the body space.

An embodiment of the extended sleeve system consists of a very rigid onepiece tulip (e.g., FIG. 2A). It is completely joined at the top by acircular ring of titanium (210) that is generated (e.g., milled) fromthe actual tulip arms themselves. The circular ring has a uniqueundercut 250 that allows the surgeon to remove the ring when he wishesby simply lifting up on the ring 210. The ring's unique undercutgeometry 250 allows the ring to release easily when the surgeon desires.The undercut also prevents leaving any sharp remnants that can cut thesurgeons hands or cause any trauma to the patient. For example, anysharp edge left at fracture point 216 is protected or shielded byprojections 221, 222. This helps protect the physician, operatingpersonnel, and the patient from sharp edge at fracture point 216.

A more detailed discussion of an embodiment of the invention, as shownin FIGS. 2A-2J, now follows. FIG. 2A includes screw 201 located at thedistal end (e.g., saddle 207) of a tulip. FIG. 2B shows the tulipwithout a screw. A circular recess 208 is near the distal end of thesystem, directly adjacent saddle 207, which provides a weakened andthinned portion that may be fatigued in order to separate arms 202, 203from the system. Windows or slots 205, 206 receive the screw and adriver, such as a screw driver, for implanting the screw into tissue(e.g., bone). The slots separate arms 202, 203 from each other. The armscollectively couple the proximal end of the tulip to the distal end ofthe tulip. Ring 210 is at the proximal end of the system.

In practice, the physician slides screw 2-1 through the orifice 209,into the distal end of the tulip, and then into saddle 207. (In otherembodiments the screw may already be located in the distal end of thesystem when the physician receives the system.) After the screw isimplanted into bone the physician will remove the ring 210 at theproximal end of the system and then fatigue the system at the distalring 208 so that the arms 202, 203 break off.

As shown in FIG. 2C, an embodiment includes a novel proximal end that iseasy for a physician to couple an instrument to and to then move thetulip about. The proximal end breaks off relatively easily due to thelow area of contact between the proximal ring 210 and the arms 202, 203.Specifically, in an embodiment the proximal end includes ring 210 thatjoins arms 202, 203 at thin locations 220, 230. Void 250 provides aspace for a physician to grip member 210 with forceps and the like. Themember 210 is then rotated away from sleeves 202, 203 directing torqueto locations 215, 216 (see FIGS. 2D, 2E). These thinned areas fail,providing a sharp edge at locations 215, 216 (see FIG. 2I). However,location 215 is protected by protuberances or projections 231, 232 andlocation 216 is protected by protuberances or projections 221, 222.

In an embodiment tabs 240, 241 (FIG. 2C) are located on proximalportions of sleeves 202, 203 to provide stability to the system (e.g.,when members 202, 203 are compressed towards one another) before andafter removal of member 210. Other embodiments do not include these tabsor projections.

FIG. 2I illustrates an embodiment after ring 210 has been removed. Sharpedge 216 is protected by rounded and smooth extensions 221, 222.Dimension 260 indicates an embodiment that provides 1.6 mm (0.06 inches)of clearance between sharp edge 216 and a space extended beyond theprotection of extensions 221, 222 (however in other embodiments 260 is0.5, 1, 1.5, 2, 2.5, 3 or more mm.

FIG. 2J illustrates an embodiment before ring 210 has been removed. Area220 is thinned in comparison to other portions of the system, therebypromoting failure at that location. In embodiment area 220 is 0.8 mm indiameter (see dimension 262). In other embodiments dimension 262 is 0.4,0.5, 0.6, 0.7, 0.9, 1.0, 1.1 or more mm. A portion of ring 210 serves asa moment arm to generate torque at location 220. The moment arm,extending from pivot point or fulcrum 220 to the outer portion of thearm, is 7.7 mm (see dimension 261). In other embodiments dimension 261is 5, 6, 7, 8, 9, 10, 11 or more mm. These dimensions, in relation toone another, are critical (in one embodiment) to generate enough torque(dependent on moment arm length) to provide failure (dependent onthinned portion 220) without undue effort from the physician while alsoproviding stability without unwanted failure at location 220 while thephysician works with the system. In an embodiment a torque of 8-10pounds force is generated to force failure of area 220. In an embodimentthe moment to break the tab would be the force multiplied by thedistance over which it is applied or 2.4-3.0 inch-pounds.

FIG. 3A shows a proximal end of a sleeve system before a linking ring isremoved and the proximal ends of sleeves are disconnected from oneanother. Specifically, ring 310 couples portion 320 of sleeve 302 to asimilarly thinned portion (not shown) on sleeve 303. Thin portion 320 isadjacent protrusions 321, 322. FIG. 3B shows a hook member seizing thelinking ring by placing hook member 351 into void 350. In otherembodiments forceps, grasps, pliers, and the like may be used to graspor secure member 310. FIG. 3C shows the hook member pulling on thelinking ring 310, thereby causing a fracture at thin portions of thesleeves (e.g., at location 316 of arm 302 and corresponding thinnedlocation on arm 303). FIG. 3D shows the system after the linking ring310 has been removed thereby leaving a sharp edge 316 protected byprotrusions 321, 322 on either side of the sharp edge 316.

Alternative embodiments exist. FIG. 4A is similar to FIG. 2C but doesnot include tabs corresponding to tabs 240, 241. FIG. 4A includes screw401 and link member 410 coupling proximal ends of sleeves 402, 403 toone another about window 406 (and another window, not shown, analogousto window 205). As with FIG. 2C, a distal recessed ring 408 is presentfor separating sleeves 402, 403 from saddle 407. Forgoing tabscorresponding to tabs 240, 241 may provide the physician with greateraccess to windows 406 (and unseen window analogous to window 205) foraccess to screw 401, tissue, and the like. As with FIG. 2C, elements421, 422 (FIG. 4D) serve to protect a sharp edge at failure area 420once linking ring 410 has been removed. As with FIG. 2C, elements 431,432 (FIG. 4E) serve to protect a sharp edge at failure area 430 oncelinking ring 410 has been removed.

Still other alternative embodiments exist. The sleeves may be longer orshorter than 5.75″. Other embodiments of sleeves may be 3, 4, 5, 6, 7,8, 9 or more inches in length. Embodiments also come in a variety ofwidths. Furthermore, an embodiment shows two points of attachment (see220, 230 of FIG. 2C) and two arms but other embodiments may include morearms (e.g., 3, 4, 5 arms) and/or more areas of coupling in the proximalend. For example, for a 3 arm embodiment the proximal ring may have 3contact points (one for each arm). Also, fewer areas of coupling arepossible.

Embodiments described herein do not necessarily include an exhaustivelisting of every component that may be included in a system. Forexample, various spacers, lock nuts, and the like may be used with thesystem although not specifically described herein.

Various embodiments provide a system where tulip arms may be separatedfrom one another via a simple rotation of a coupling member until thatcoupling member fatigues and fails. An embodiment includes a void forreceiving a tool to allow the tool to securely attach to the ring and,while still in the void, cause the ring to pivot, fail, and separatefrom the tulip arms (but other embodiments, such as that of FIG. 4Crequire no void because tabs 240, 241 are not present and window 406provides ample space to access and secure element 410). The rotationforce (torque) is beyond minimal (so the physician does not accidentallyseparate the ring from the arms) but is still less than overlyrestrictive due to, for example, the moment arm that extends along thering (e.g., dimension 261 of FIG. 2J) to the thinned severance pointswhere the ring couples to the arms. This makes for a far easierseparation for the physician, and the designated failure points for theproximal ring allow for a consistent experience for the physician (e.g.,the ring fails at the same two places most every time the systems areused).

In another embodiment a single failure point is possible. For example,an embodiment similar to FIG. 2C includes no proximal ring 210 butinstead couples the two arms at a single point. Thus, instead of theseparation shown in FIG. 2C, in an alternative embodiment thatseparation is instead a seam. The physician may simply compress the twoarms towards one another (e.g., with forceps) causing the arms to eachrotate away from the seam, fatigue the seam, cause the seam to fail, andtherefore separate the arms from one another. In another embodiment, thephysician may simply spread the arms away from each other, causing thearms to each rotate towards the seam, fatigue the seam, cause the seamto fail, and therefore separate the arms from one another.

An embodiment includes a method of using an extended sleeve system. Anembodiment includes inserting a K-wire through a cannulated needlesheath. Once the guide wire is inserted and firmly docked, the targetingneedle is removed. With the K-wire in place a series of dilators areplaced over the wire to create a working portal. At this point, theinner dilators are removed, leaving the outer dilator behind forsubsequent surgical steps. A cannulated pedicle tap can then be passedover the K-wire. Fluoroscopy may be used to verify the position of thetap in relation to the K-wire, making sure that the tap does not advancefurther than the wire. The physician may pass the screw inserter throughan extender sleeve of the screw and into a hex head. With the screwconstruct properly connected to the screw inserter, the screw may bepassed over the K-wire down to the pedicle. The screw is advanced underfluoroscopic guidance until the screw reaches the posterior wall of thevertebral body. At this point, the K-wire is removed and the screw isadvanced until the polyaxial head of the screw sits snugly against thebase of the facet joint. At this time, the screw inserter and dilatormay be removed, leaving the screw with the extender sleeve stillattached. The previous surgical steps may be repeated in order to placea second pedicle screw (and other screws if need be). Once both screwsare in position, the extender sleeves are rotated so that the slots faceone another (i.e., so that windows such as windows 205, 206). The rodmeasurement tool is lowered down the extender sleeves to measure for therod length.

After selecting the appropriate length rod, the physician uses the rodholder to guide the linkage rod down the two extended tabs on thepedicle screws and into the base of each screw. The rod holder can beused to adjust the cephalad/caudad position of the rod within thescrews. After the linkage rod connects the screws the sleeves may beremoved by removing element 210 (FIG. 2C) and then sleeves 202, 203.

FIGS. 5A, 5B, 5C depict a method of implanting an embodiment of theinvention. FIG. 5A depicts three tulip structures 570 with protectiveproximal rings (e.g., ring 210 from FIG. 2C) already removed. The tulipstructures 570 are all passing through tissue 574 and contactingportions of spine 573. Screws are deployed into the spine and arelocated (but not shown) at the distal ends of tulip structures 570. InFIG. 5B the physician has passed the rod 572 and inserter assembly 571through the towers (i.e., tulips 570). The physician has seated thedistal tip of the rod 572 on to the saddle of a tulip to beginpercutaneous tunneling through tissue 574. FIG. 5B shows the physicianaccessing the channels (e.g., spaces formed by windows 205, 206) betweensleeves (e.g., 202, 203) for all three of the tulip structures. Morespecifically, the physician tunnels the rod through each tulip, byrotating the shaft and handle of the inserter 571 through each tower.This helps align and tunnel the rod through tissue and the towers. FIG.5C shows the physician using a placement tool 571 (coupled to handle575) to implant a linkage rod 572 (that will link three differentpedicle screws) into its final position. Set screws (not shown) may thenbe placed down the tulips and over the rod 572 to help stabilize thespine (or any other bone portions, such as separate pieces of a femur inother embodiments).

FIG. 6 depicts a method of implanting an embodiment of the invention.FIG. 6 depicts three tulip structures 670 with protective proximal rings(e.g., ring 210 from FIG. 2C) still present. The physician passes thetip of the rod to the bottom of the tulip and then tunnels the rodthrough the tissue from tower to tower. The tulip structures 670 are allpassing through tissue 674 and contacting portions of spine 673. Screwsare deployed into the spine and are located (but not shown) at thedistal ends of tulip structures 670. The physician accesses the channels(e.g., spaces formed by windows 205, 206) between sleeves (e.g., 202,203) for all three of the tulip structures. The physician uses aplacement tool 671 (coupled to handle 675) to implant a linkage rod 672that will link three different pedicle screws. Set screws (not shown)may then be placed down the tulips and over the rod 672 to helpstabilize the spine (or any other bone portions, such as separate piecesof a femur in other embodiments). In this embodiment the physician mayhave preferred to implant the rod 672 while the proximal rings are stillintact because the proximal rings (e.g., 210) maintain stability of thesleeves and keep the sleeves from prematurely fracturing about distalrecesses (e.g., 208) adjacent a saddle structure (e.g., 207). Thephysician may locate the placement device 670 adjacent tulips 670 inorder to avoid tabs such as tabs 240, 241 of FIG. 2C.

FIGS. 7A, 7B, 7C depict a method of implanting an embodiment of theinvention. FIG. 7A depicts tulip structures 770 with protective proximalrings (e.g., ring 210 from FIG. 2C) still present. Specifically, thephysician has inserted the rod into the first tower. Note how the towersare rotated 180 degrees from one another to allow the greatest access tothe channels of the tulips (i.e., the “closed” portions of the rings 210are located “outermost” and the “open” portions of the rings 210 arelocated adjacent one another). In this embodiment the physician may havepreferred to implant the rod 772 while the proximal rings are stillintact because the proximal rings (e.g., 210) maintain stability of thesleeves and keep the sleeves from prematurely fracturing about distalrecess (e.g., 208) adjacent a saddle structure (e.g., 207). The tulipstructures 770 are all passing through tissue 774 and contactingportions of spine 773. Screws are deployed into the spine and arelocated (but not shown) at the distal ends of tulip structures 770. FIG.7B shows the physician accessing the channels (e.g., spaces formed bywindows 205, 206) between sleeves (e.g., 202, 203) for the tulipstructures. FIG. 7C shows the physician using a placement tool 771 toimplant a linkage rod 772 that will link pedicle screws. Set screws (notshown) may then be placed down the tulips and over the rod 772 to helpstabilize the spine (or any other bone portions, such as separate piecesof a femur in other embodiments). The physician may locate the placementdevice 770 within channels of tulips 770 easily using an embodiment,such as that of FIG. 4A, which does not include tabs such as tabs 240,241 of FIG. 2C. In other words, without tabs 240, 241 the tool 771 androd 772 can easily passed within channels of the tulips.

Materials for embodiments of the tulips may include, for example, cobaltalloys (e.g., cobalt chromium), titanium alloys (e.g., nickel titaniumalloy (Nitinol)), commercially pure titanium, Ti 6Al-4V Eli,polyetheretherketone (PEEK), stainless steel, ceramics (e.g., aluminumoxide, zirconia, calcium phosphates), polymers (e.g., silicones,poly(ethylene), poly(vinyl chloride), polyurethanes, polylactides),natural polymers (e.g., collagen, gelatin, elastin, silk,polysaccharide, hydrogels), and the like.

An embodiment includes an orthopedic implant system comprising: a tulipincluding (a) an orifice at a distal end portion of the tulip to coupleto an anchor element, (b) an open slot to receive a linkage, (c) firstand second side walls that collectively define at least a portion of theopen slot, and (d) a ring that couples the first side wall to the secondside wall at a proximal end portion of the tulip; wherein the ringcouples to the first side wall at a thinned first proximal fulcrum andto the second side wall at a thinned second proximal fulcrum and thering pivots about the first and second proximal fulcrums when the ringis forced proximally; wherein the first side wall includes a firstthinned portion forming a first distal fulcrum about which the firstside wall rotates after the ring is removed from the tulip but notbefore the ring is removed from the tulip; wherein the second side wallincludes a second thinned portion forming a second distal fulcrum aboutwhich the second side wall rotates after the ring is removed from thetulip but not before the ring is removed from the tulip; wherein thefirst side wall includes a first sidewall projection that projects pastthe first proximal fulcrum and the second side wall includes a secondsidewall projection that projects past the second proximal fulcrum. Afulcrum includes the point on which a lever rests or is supported and onwhich the lever pivots.

An embodiment includes an orthopedic implant system comprising: a tulipincluding (a) an orifice at a distal end portion of the tulip to coupleto an anchor element, (b) an open slot to receive a linkage, (c) firstand second side walls that collectively define at least a portion of theopen slot, and (d) a ring that couples the first side wall to the secondside wall at a proximal end portion of the tulip; wherein the ringcouples to the first side wall at a thinned first proximal fulcrum andto the second side wall at a thinned second proximal fulcrum and thering pivots about the first and second proximal fulcrums when the ringis forced proximally; wherein the first side wall includes a firstthinned portion forming a first distal fulcrum about which the firstside wall rotates after the ring is removed from the tulip; wherein thesecond side wall includes a second thinned portion forming a seconddistal fulcrum about which the second side wall rotates after the ringis removed from the tulip; wherein the first side wall includes a firstsidewall projection that projects past the first proximal fulcrum andthe second side wall includes a second sidewall projection that projectspast the second proximal fulcrum. A fulcrum includes the point on whicha lever rests or is supported and on which the lever pivots.

An embodiment includes wherein the first side wall includes anadditional first sidewall projection that projects past the firstproximal fulcrum and the second side wall includes an additional secondsidewall projection that projects past the second proximal fulcrum.

An embodiment includes wherein the first proximal fulcrum is proximal tothe first sidewall projection and distal to the additional firstsidewall projection.

An embodiment includes wherein the ring includes a midpoint and thefirst and second sidewalls form a void directly distal to the midpoint.

An embodiment includes wherein the void is entirely collinear with thefirst and second sidewalls.

An embodiment includes wherein the void includes a sidewall portion thatis non-collinear with either of the first and second sidewalls.

An embodiment includes wherein a void is located directly between aproximal most portion of the first and second sidewalls and a distalportion of the ring such that an axis, parallel to a major axis of thesystem, intersects the ring and one of the first and second sidewalls.

An embodiment includes wherein the first sidewall includes a first axisparallel to a long axis of the tulip and the first axis intersects thefirst sidewall projection but not the first or second proximal fulcrums.

An embodiment includes wherein the first side wall includes anadditional first sidewall projection that projects past the firstsidewall projection and the second side wall includes an additionalsecond sidewall projection that projects past the second sidewallprojection.

An embodiment includes wherein the additional first sidewall projectionis proximal to the first sidewall projection.

An embodiment includes wherein the ring is monolithic with the first andsecond sidewalls.

An embodiment includes wherein portions of the first and secondsidewalls are threaded proximal to the first and second thinnedportions.

An embodiment includes wherein the first and second thinned portions arerecessed inwardly from exterior walls of the first and second sidewalls.

An embodiment includes wherein an exterior wall of the ring is collinearwith at least a portion of an exterior wall of the first sidewall.

An embodiment includes wherein an exterior wall of the first proximalfulcrum extends radially no further than an exterior wall of the firstsidewall projection.

An embodiment includes wherein the ring includes a midpoint and thefirst and second proximal fulcrums are equidistant from the midpoint.

An embodiment includes wherein the first and second proximal fulcrumseach respectively project away from main portions of the first andsecond sidewalls and voids are included immediately proximal and distalto each of the first and second proximal fulcrums.

An embodiment includes wherein a maximum diameter of the first proximalfulcrum is less than 1.0 mm.

An embodiment includes wherein the first proximal fulcrum is configuredto fail when the ring is forced proximally.

An embodiment includes wherein the first and second sidewall projectionsare rounded.

An embodiment includes an orthopedic implant system comprising: aconduit including (a) an orifice at a distal end portion of the conduitto couple to an anchor element, (b) an open slot to receive a linkage,(c) first and second side walls, disposed parallel to a long axis of theconduit, that collectively define at least a portion of the open slot,and (d) a lever, disposed parallel to a short axis of the conduit, thatcouples the first side wall to the second side wall at a proximal endportion of the conduit; wherein the lever couples to the first side wallat a first proximal fulcrum and to the second side wall at a secondproximal fulcrum and the lever pivots about the first and secondproximal fulcrums when the lever is forced proximally; wherein the firstside wall includes a first sidewall projection that projects past thefirst proximal fulcrum and the second side wall includes a secondsidewall projection that projects past the second proximal fulcrum.

An embodiment includes wherein the first side wall includes anadditional first sidewall projection that projects past the firstproximal fulcrum and the second side wall includes an additional secondsidewall projection that projects past the second proximal fulcrum.

An embodiment includes wherein the first proximal fulcrum is proximal tothe first sidewall projection and distal to the additional firstsidewall projection.

An embodiment includes wherein the first side wall includes anadditional first sidewall projection that projects past the firstsidewall projection and the second side wall includes an additionalsecond sidewall projection that projects past the second sidewallprojection.

An embodiment includes wherein the ring includes a midpoint and thefirst and second proximal fulcrums are equidistant from the midpoint.

An orthopedic implant system comprising: a conduit including (a) anorifice at a distal end portion of the conduit to couple to an anchorelement, (b) an open slot to receive a linkage, (c) first and secondside walls, disposed along a long axis of the conduit, that collectivelydefine at least a portion of the open slot, and (d) a lever, disposedalong a short axis of the conduit, that couples the first side wall tothe second side wall at a proximal end portion of the conduit; whereinthe lever couples to the first side wall at a first proximal fulcrum andto the second side wall at a second proximal fulcrum and the leverpivots about the first and second proximal fulcrums when the lever isforced proximally; wherein the first side wall includes a first sidewallprojection that projects past the first proximal fulcrum and the secondside wall includes a second sidewall projection that projects past thesecond proximal fulcrum. In such an embodiment “along” may be mean“parallel” but in other embodiments that is not necessarily the case.

While the present invention has been described with respect to a limitednumber of embodiments, those skilled in the art will appreciate numerousmodifications and variations therefrom. It is intended that the appendedclaims cover all such modifications and variations as fall within thetrue spirit and scope of this present invention.

What is claimed is:
 1. An orthopedic implant system comprising: aconduit having a proximal half of the conduit directly connected to adistal half of the conduit; wherein the conduit includes: (a)(i) anorifice located in the distal half of the conduit; (a)(ii) an open slotto receive a linkage; (a)(iii) first and second side walls thatcollectively define at least a portion of the open slot; and (a)(iv) alever; wherein the lever is located in the proximal half of the conduit;wherein the open slot is located in the proximal and distal halves ofthe conduit; wherein the lever couples to: (b)(i) the first side wall ata first location, and (b)(ii) the second side wall at a second location;wherein in response to the lever being forced proximally the lever isconfigured to disconnect from: (c)(i) the first sidewall at the firstlocation, and (c)(ii) the second sidewall at the second location;wherein the first side wall includes a first void immediately adjacentthe first location; wherein the first side wall includes first andsecond projections that are both immediately adjacent the first void;wherein an axis intersects the first void, the first projection, and thesecond projection.